The present invention relates to a method of and an arrangement for elongating and relaxing a stud arranged in an object, such as for example in a flange or the like.
Methods of the above mentioned general type are known in the art. For example, in order to elongate or relax a stud, a mechanical nut having two elements is utilized, and the elements are moved relative to one another in opposite axial directions to elongate the stud or to relax it. There are however many applications where no gaskets are used to seal the two flange portions or where the stud is oversized relative to the required clamping force. Therefore, with a steel-to-steel flange connection there is no compression feasible, and with an oversized stud there is no stud elongation feasible, and thus axial movement of one of the parts becomes possible.
My U.S. Pat. No. 5,341,560 discloses a method of elongating and relaxing a stud in accordance with which a first part engages the stud, a friction element is connected with the first part, a second part is connected with the first part, and a holding force is applied to the first part while an opposite active force is applied to the second part via corresponding first and second engaging means so that while the second part turns, the first part moves in the axial direction and elongates (relaxes) the stud. This method eliminates the disadvantages of the prior art. In some instances, however, the first part can be unaccessible, or it might be undesirable to apply the holding force to the first part. In any event, the mechanical tensioner described in my above identified patent can cooperate only with such a tool which has a central structure designed to apply a holding force to the first part, and an offset or surrounding structure designed to apply a turning force to the second part. Such tools are special tools, since in conventional tools the situation is just opposite. In the center of the tool there is always a drive part, while the housing which can be used to apply a holding force or to carry a holding element is located offset relative to the central drive part or surrounds the drive part. It is believed to be clear that in many cases it is not desirable to provide a special tool for such a mechanical tensioner.